(1) Field of the Invention
The present invention relates to transmission type or semi-transmission type liquid crystal display elements and liquid crystal display devices using such a liquid crystal display element.
(2) Related Art Statement
Conventional liquid crystal panels where an array of protruding micro-lenses having a recess at the top is formed on the surface of a transparent substrate on the backlight side so that fewer moiré fringes are produced due to an optical sheet having a regular structural pattern have been proposed (see, for example, Patent Document 1).
In addition, conventional transmission type projection screens made of a Fresnel lens sheet and a lenticular lens sheet where a liquid crystal panel is used together with a projector used as a light bulb, and lenticular lenses are formed at irregular intervals on the lenticular lens sheet so that there are fewer moiré effects resulting from mutual effects between a number of pixels in the liquid crystal panel projected onto and enlarged on the transmission type projection screen, and the lenticular lenses having sampling effects have been proposed (see, for example, Patent Document 2).
As is pointed out in Patent Document 1, a problem arises with liquid crystal display devices such that there are moiré effects in the regular structure on the backlight, for example, the structure for light emission formed on the prism sheet or the light guiding plate, when a regular micro-lens array is provided between the liquid crystal display element and the backlight.
In addition, in Patent Document 1, there are fewer moiré fringes when an array of protruding micro-lenses in a particular form having a recess at the top is used, and a problem arises where it is difficult to create this array of micro-lenses in a complex form.
Furthermore, as shown in Patent Document 2, there are fewer moiré effects in the regular structure when the lenticular lenses are at irregular intervals. However, in the case where micro-lenses are arranged in an array so as to match the intervals of the pixels in the liquid crystal display device as in Patent Document 1, it is necessary for the lenses to be at regular intervals, and this concept cannot be applied.
[Patent Document 1] Japanese Unexamined Patent Publication 2006-47360
[Patent Document 2] Japanese Unexamined Patent Publication H6 (1994)-130497